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Seafloor ambient noise in the Arctic Ocean is related to sea ice. The characteristics of low‐frequency seafloor ambient noise (<10 Hz) in the northern Chukchi Sea have rarely been reported. Here, we investigated the seafloor ambient noise recorded using ocean‐bottom seismometers in the northern Chukchi Sea under four different sea ice‐concentration periods from 3 to 23 August 2020, in the 11th Chinese National Arctic Research Expedition. The causes and mechanisms of the changes in seafloor ambient noise that correspond to the variation in sea ice concentration were discussed. The energy of infragravity waves and primary microseisms is weak compared with other oceans. Combined with the analysis of land station, we argue that the variations in sea ice extent have little effect on the energy of the primary microseisms and infragravity waves. The power of secondary microseisms is growth with the loss of sea ice and is influenced by storms. We find that a high concentration of sea ice can impede the process of storm‐sea surface interaction, which in turn affects the power of microseisms inspired by storm. [ABSTRACT FROM AUTHOR]

Background: Reperfusion therapy is the most effective approach to resolve coronary occlusion, but myocardial injury caused by excessive inflammation during myocardial ischemia–reperfusion will also pose a new threat to health. Our prior study revealed the expression pattern of interleukin‐38 (IL‐38) in the peripheral blood serum of patients with ischemic cardiomyopathy and the role of IL‐38 in acute myocardial infarction in mice. However, its role and potential mechanisms in myocardial ischemia/reperfusion injury (MIRI) remain to be determined. Methods and Results: The left anterior descending artery of C57BL/6 mice was transiently ligated to induce the MIRI model. We found that MIRI induced the expression of endogenous IL‐38, which was mainly produced by locally infiltrating macrophages. Overexpression of IL‐38 in C57BL/6 mice attenuated inflammatory injury and decreased myocardial apoptosis after myocardial ischemia–reperfusion. Furthermore, IL‐38 inhibited lipopolysaccharide‐induced macrophage inflammation in vitro. Cardiomyocytes cocultured with the supernatant of IL‐38‐ and troponin I‐treated macrophages showed a lower rate of apoptosis than controls. Conclusions: IL‐38 attenuates MIRI by inhibiting macrophage inflammation. This inhibitory effect may be partially achieved by inhibiting the activation of NOD‐like receptor pyrin domain‐related protein 3 inflammasome, resulting in decreased expression of inflammatory factors and reduced cardiomyocyte apoptosis. [ABSTRACT FROM AUTHOR]

The Solomon Sea Basin is a Cenozoic back‐arc spreading basin within the convergence system of the Pacific and Indo‐Australian plates. Against the background of subduction polarity reversal, the current Solomon Sea Basin gradually formed a rhombic morphology with the subduction of the basin along the New Britain Trench and the Trobriand Trough. By analyzing the vertical gravity gradient, natural earthquake and seismic reflection data, this study determines the structural characteristics of the Solomon Sea Basin. It was found that the tectonics of the basin are characterized by the original expansion structure within the central part in addition to the structure induced by the latest subduction along the basin margin. The original spreading structure of the basin presented an east–west linear graben and horst controlled by normal faults during the basin expansion period. As a result of the subduction and slab‐pull of the Solomon Sea Basin, extensional structure belts parallel to the New Britain Trench formed along the basin margin. [ABSTRACT FROM AUTHOR]

Faraday rotation angle formula for polarized light propagating in magneto-optic medium is investigated theoretically. Based on the Biot-Savart Law and Maxwell's equations, a calculation model for electromagnetic field in solenoid paraxial region is deduced. Taking advantage of this model, together with the Bessel functions, the axial magnetic field in a typical medium is calculated and analyzed. In addition, to thoroughly analyze the influence mechanisms of the incident wavelength and temperature on the Verdet constant and then uncover its essence, a hypothesis which suggests the Faraday effect results from the combination of various factors is proposed. Furthermore, a theory of wave-transition contribution to the Verdet constant is deduced by adopting the theory of wave-particle duality. Taking the typical diamagnetic material ZF1 and paramagnetic material TGG as examples, the deduced theory together with the corresponding models is tested and verified by analyzing the relevant parameters and the test data. At last, a testing system for magneto-optical rotation together with its finite element model is introduced.

The New Britain‐North Solomon subduction system is located at the convergence boundary between the Indo‐Australian and Pacific plates. In the Cenozoic, the subduction system gradually evolved into a complex system containing the trench, arc, back‐arc basin and oceanic plateau with the subduction and collision of the Ontong Java Plateau, which becomes one of the best places to explore the subduction dynamics. We attempt to illustrate the morphology of the Solomon Sea slab's response to the collision of the Ontong Java Plateau along the New Britain Trench through the hypocentral distribution, focal mechanisms and density structure from the gravity anomalies. According to the hypocenters and focal mechanisms, the focal stress field of the subducted Solomon Sea Plate along the New Britain Trench is analysed and the spatial distribution pattern of the plate is determined. We found that the maximum subduction depth of the Solomon Sea Plate gradually decreases from ~600 to ~400 km and the morphology of the slab changes from the steep‐dipping subduction to slab roll‐back from the Green and Buka Islands to the Bougainville Islands. Indicated by the analysis of seismicity and gravity anomalies, the spatial differences of the subduction pattern in the Solomon Sea Plate along the New Britain Trench are closely correlated with the block of the upper mantle in the Ontong Java oceanic Plateau, which is characterized by a tendency of thickening from NW to SE along the North Solomon Trench. [ABSTRACT FROM AUTHOR]

The effects of elevated CO2 concentration on photosynthetic gas exchange parameters and chlorophyll fluorescence parameters in leaves of Calamagrostis angustifolia seedlings under drought stress were studied through control of different CO2 concentrations (370 and 700 μmol·mol−1) with an artificial OTC climate chamber. The results demonstrated that: Under non-drought conditions, although the stomatal conductance (Gs) and transpiration rate (Tr) decreased slightly as the CO2 concentration increased, while the net photosynthetic rate (Pn) increased significantly, resulting in a significant increase in leaf water use efficiency (WUE). However, the effect of elevated CO2 concentration on PSII reaction center activity was insignificant under non drought conditions. Under severe drought stress, the amount of active reaction centers per unit area and the proportion of PSII absorbed light energy for photosynthetic electron transfer increased, while the proportion of PSII absorbed light energy for heat dissipation decreased, providing energy guarantee for effective fixation of CO2 as dark reaction. In conclusion, elevated CO2 concentration could improve the water use efficiency of C. angustifolia seedlings under normal water and drought stress, and the elevated CO2 concentration could improve the drought resistance ability of C. angustifolia seedlings through PSII function improvement under severe drought stress. [ABSTRACT FROM AUTHOR]